Conventionally, a torsion spring counterbalancing mechanism may be used with an overhead door to counterbalance a weight of the overhead door when moving the overhead door during between an open position and a closed position. When the torsion spring counterbalancing mechanism is installed, one or more springs forming a portion of the torsion spring counterbalancing mechanism need to be pretensioned with an amount of counterbalancing force. Further, following initial installation, adjustment of the amount of counterbalancing force may be necessary to repair or replace the torsion spring counterbalancing mechanism.
A conventional method used to adjust the amount of counterbalancing force in one or more springs forming a portion of the torsion spring counterbalancing mechanism may be dangerous. Winding rods are typically inserted into a spring end cone, a rotational force is applied to the one or more springs, the spring end cone is disengaged from a torsion shaft, and the amount of counterbalancing force is one of increased and decreased. When a first winding rod is inserted in the spring end cone, the rotational force may be applied to the one or more springs. Using a second winding rod and an iterative process, the one or more springs may be wound or unwound. Such a process may be dangerous, as the winding rod will rotate quickly when the one or more springs are pretensioned and the winding bar is unrestrained.
To reduce such a danger, it is known in the prior art to employ a spring winder having a worm drive gear engaged with a worm wheel to adjust the amount of counterbalancing force. The worm wheel is fitted about a center portion of the torsion shaft and the worn drive gear is rotated to adjust the amount of counterbalancing force in the one or more springs. However, when the one or more springs are pretensionsed, the worm wheel may tilt or move along its axis as it resists the counterbalancing force. When the worn wheel tilts or moves along its axis, the worn drive gear may become disengaged or misaligned, rendering such a spring winder inoperable.
It is also known in the prior art to locate the spring winder having the worm drive gear engaged with the worm wheel at an end of the torsion shaft to militate against movement of the worm wheel. In such an arrangement a separate spring winder is employed for each spring, and the spring winder is subject to a thrust force of the spring. Balancing the thrust force of the spring may extend a service life of the spring significantly. Further, in such an arrangement, non-conventional cable drums are employed to house a portion of the spring winder. The spring winder having the worm wheel at an end of the torsion shaft increases a cost and a complexity of the counterbalancing mechanism while decreasing a service life of the one or more springs.
It would be advantageous to develop a spring winding device that does not require pretensioning using winding rods, maintains rigidity and alignment when a counterbalancing force is applied, and decreases a cost and a complexity of a counterbalancing mechanism the spring winding device is incorporated in.